When machining articles to a desired shape it is often necessary to rotate the article (usually termed the workpiece) so that symmetrical machining can be achieved of a given cross section.
Rotation of the workpiece to be machined can be achieved by securing the workpiece into a rotating chuck. However if the workpiece is not centralised correctly within the clamaping jaws of the chuck, it will not rotate in a `true` fashion and machining will be inaccurate.
Alternative methods of transmitting rotation involve the use of a tailstock and a headstock to support the article between centers, the headstock transmitting the rotation, directly or indirectly to the workpiece.
The interengagement between the workpiece and the headstock or driver may be subject to misalignment and offset, which will introduce errors in the machining.
An improved drive transmitting device which will not transmit misalignment or offset to the workpiece is described in U.S. patent application Ser. No. 08/737,974.